The present invention relates generally to duct assemblies for transporting pressurized fluid such as heating and cooling air, and more particularly to an apparatus and method for use in making a duct assembly having permanently attached flange connectors.
Duct assemblies used to transport pressurized fluid in buildings (e.g., for forced air HVAC systems) are conventionally formed in sections and secured together to form longer spans as needed. A duct section is typically formed of sheet metal into a rectangular shape having four sides and bent or seamed corners at the intersections of the sides. A flange extends essentially perpendicularly outward from each side at both ends of the duct section. The sections are positioned end-to-end so the flanges of one section align with the flanges of the adjacent section and the aligned flanges are fastened together to form the duct assemblies. The flanges which are formed as part of each duct section are not continuous. Rather, there are gaps at each place on the duct sections where adjacent flanges meet for manufacturing convenience. Stamped corner pieces are inserted in channels formed in each flange so they span the gap at each place on the duct section where adjacent flanges meet. When the duct sections are positioned end-to-end, the stamped corner pieces of one duct section are aligned with stamped corner pieces of the adjacent duct section. Fasteners are inserted through holes extending through the stamped corner pieces to clamp the duct sections together. Frequently, gaskets are placed between aligned flanges to achieve an airtight seal and clips are used to hold the aligned flanges together between the stamped corner pieces.
Stamped corner pieces are sometimes inserted in the duct section at one location and transported to another location for attachment to other duct sections to form duct assemblies. The corner pieces are snapped into the flanges, which are formed with return bends at their free ends to bear against the corner piece with a spring force to hold the corner pieces in the flange. It is also known to press in the corner pieces and crimp over the return bends of the flanges to secure them. However in many cases, the snap connection of the corner piece into the flange is not completely secure, even when crimping is used. Not only does this allow the corner pieces to become separated from the flanges more easily, but it also allows adjacent flanges of the duct assembly to move independently of each other. When the corner pieces become separated from the flanges, additional time is required to reinsert the corner pieces in the flanges. Moreover, if the corner pieces become separated when the duct sections are overhead, the corner pieces can fall on workers below. Still further, if the corner pieces move independently from the flanges, adjacent flanges of the duct assembly can move independently from each other permitting the duct sections to move with respect to each other thereby allowing fluid to leak from between the joints. Finally, the insertion of the corner pieces into the flanges provides no rigid interconnection of adjacent flanges and therefore minimal angular rigidity to the joint between the duct sections or to the duct assembly in general.
Among the several objects and features of the present invention may be noted the provision of a duct assembly which has improved strength at its joints; the provision of such a duct assembly which maintains a tight seal at the joint; the provision of such a duct assembly which has fewer parts constituting the joint; the provision of a method and apparatus for quickly and inexpensively attaching connection elements to flanges of duct sections to facilitate interconnection of duct sections; and the provision of a method and apparatus for quickly and inexpensively preparing duct sections for interconnection.
Briefly, the present invention includes apparatus for making a patterned strip for use in connecting sections of duct. The patterned strip has opposite lateral sides extending parallel to a longitudinal centerline of the strip and evenly spaced slots extending inward from each of the opposite lateral sides of the strip toward the longitudinal centerline. Each of the slots is obliquely aligned with respect to the lateral sides of the strip. The apparatus comprises a guide for guiding the strip in a longitudinal direction and a slotting tool arranged relative to the guide for making a laterally spaced pair of slots in the strip. In addition, the apparatus includes an indexing device arranged relative to the guide for indexing the strip a predetermined longitudinal distance before making subsequent laterally spaced pairs of slots in the strip to make the evenly spaced slots in the strip.
In another aspect, the present invention includes apparatus for attaching a leading edge portion of a patterned strip to a flange of a section of duct for facilitating connection of sections of duct in end-to-end relation. The apparatus comprises a fixture for locating a section of duct and a guide adapted to receive the patterned strip. The guide is arranged relative to the fixture to guide the patterned strip toward the fixture. In addition, the apparatus includes a fastening tool arranged relative to the fixture for affixing the duct flange and a leading edge portion of the patterned strip to each other and a shear arranged relative to the fixture for shearing the leading edge portion of the patterned strip from the patterned strip.
Further, a method of the present invention for attaching an element of a patterned strip to a flange of a section of duct includes the step of piercing a portion of the duct flange through a hole in the connector element. An area of the duct flange adjacent the hole is upset in a direction parallel to the pierced portion of the duct flange. Then the portion of the duct flange pierced through the hole against the element is flared to fasten the duct flange and the element to each other. The method also includes the step of at least partially flattening the upset area of the duct flange to tighten the connection between the duct flange and the element.
In addition, the present invention includes a method for attaching a leading edge portion of a patterned strip to a flange of a section of duct for facilitating connection of sections of duct in end-to-end relation. The method includes the steps of guiding a patterned strip toward a location where the strip is to be attached to the flange at an end of the section of duct and attaching the leading edge portion to the duct flange. Finally, the method includes the step of separating the leading edge portion from the strip.
Moreover, the present invention includes a patterned strip for use in connecting sections of duct in end-to-end relation. The strip includes an elongate sheet having opposite lateral sides extending between opposite ends spaced along a longitudinal centerline of the sheet. The sheet has evenly spaced slots extending inward from each of the opposite lateral sides of the sheet toward the longitudinal centerline. Each of the slots extends at an angle with respect to the side of the sheet from which it extends. Further, each of the slots is laterally spaced from another of the slots extending inward from the opposite side of the sheet. Each of the slots and the corresponding slot laterally spaced therefrom are oriented at an angle with respect to each other.
Still further, the present invention includes a method for attaching connector elements to flanges at ends of duct sections to facilitate connection of the duct sections in end-to-end relation. The method includes placing an element in contact with a duct section flange of the duct section. The element is permanently affixed to the duct section flange by moving fastening means from at least one of the element and the flange through another of the element and the flange to make an integral connection of the element to the duct section flange.
In yet another aspect of the present invention, a duct section has sides extending between opposite ends. Each of the sides joins an adjacent side and has a flange extending laterally outward from each end. Each of the flanges includes a hole extending therethrough. Each of the holes is spaced from where the sides of the duct section are joined by a distance of between about one half inch and about five inches.
In addition, this invention is a duct assembly for transporting pressurized fluid therethrough. The assembly includes first and second duct sections. Each of the duct sections has sides extending between opposite ends. Each of the sides joins an adjacent side and has a flange extending laterally outward from each end. The first and second sections are positioned in end-to-end relation so the flanges extending outward from one of the ends of the first section face the flanges extending outward from one of the ends of the second section thereby defining aligned flange pairs and so sides of the first duct section are generally aligned with the sides of the second duct section. The duct assembly also includes a plurality of connector pairs. Each connector pair is positioned at one place on the first and second duct sections where the sides join. Each of the connector pairs comprises a first connector spanning adjacent flanges of the first duct section and a second connector spanning adjacent flanges of the second duct section. The first and second flange connectors are positioned on opposite faces of an adjacent flange pair so the flange pair is positioned between the first and second connectors. In addition, the duct assembly includes fasteners. Each of the fasteners extends through one of the connector pairs and one of the flange pairs to connect the flange pairs.
In another aspect, the duct assembly of the present invention includes a duct section having sides extending between opposite ends. Each of the sides join an adjacent side and has a flange extending laterally outward from each end. The assembly also includes connectors. Each of the connectors is fixedly connected to adjacent flanges at the end of the duct section to prevent movement between the adjacent flanges of the duct section.
Finally, a method of the present invention for assembling a duct assembly includes the steps of positioning first and second sections in end-to-end relation so the flanges extending outward from one of the ends of the first section face the flanges extending outward from one of the ends of the second section thereby defining aligned flange pairs and so sides of the first duct section are aligned with the sides of the second duct section. In addition, the method includes positioning a connector pair comprising first and second connectors, the first connector spanning adjacent flanges of the first duct section and the second connector spanning adjacent flanges of the second duct section and so the first and second connectors are positioned on opposite faces of an adjacent flange pair so the flange pair is positioned between the first and second connectors. The connector pair and one of the flange pairs are securely fastened together to connect the flange pair.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.